Telescoping bone screw

ABSTRACT

A bone screw for treating a bone fracture having a detent assembly on a body portion thereof. The detent assembly includes a detent member that is movable between a first and second position. The detent assembly operative to secure the body whereby said plunger portion moves independent of said body. The bone screw may also include a plunger assembly having a plunger with a threaded portion and a plunger portion. The plunger portion is slidably disposed within a chamber of the body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/368,060 filed on Feb. 7, 2012, currently pending, which is acontinuation-in-part of U.S. patent application Ser. No. 13/045,470filed on Mar. 10, 2011, currently pending, which claims the benefit ofU.S. Provisional Application Ser. No. 61/312,251 filed Mar. 10, 2010.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure relates generally to bone treatment devices, andmore particularly to a bone screw used to treat a bone fracture whereinthe bone screw is suitable for treating fractures of the femur includingtrochanteric, intertrochanteric and femoral neck fractures.

2. Description of Related Art

Orthopedic fixation systems used for stabilizing a fracture ofteninclude an internal fixation device, typically an elongated implant suchas a nail, screw or pin, inserted into the intramedullary canal of thebone to stabilize the fracture and promote healing. Such fixationsystems are suitable for use in treating fractures of the neck, head,intertrochanter, subtrochanteric, pathologic and certain ipsilateralshaft and neck fractures of the femur. The femur generally includes anelongated shaft, a ball shaped head that fits into the hip socket and aneck connecting the ball to the shaft. The shaft also includes a greatertrochanter and a lesser trochanter.

For example, if the neck of the femur sustains a fracture a bone nail isinserted into the intramedullary canal and a bone screw inserted throughan aperture in the head of the nail. The bone screw spans the fractureand threadably engages the femoral head. Typically, a smooth bore formsthe aperture in the end of the nail. The bone screw extends through thesmooth bore and rotates as it threadably engages the femoral head. Oncethe bone screw is suitably tightened, it is left in place during thehealing process. In some instances, for example when the patient putsweight on the hip, the fracture will compress or settle. Thus, bonescrew migration is one problem that may occur during the healingprocess. Specifically, when the patient puts weight on the hip thefemoral head may move with respect to the femur; that is, the femoralhead may slide medially or laterally at the fracture. The movement maybe due to weakness in the bone, bone deterioration, misalignment of thefracture or other factors.

Depending upon the type of connection or engagement between the bonescrew and the bone nail, movement of the femoral head with respect tothe femur may result in “cut-out,” that is the externally threaded endof the bone screw cuts or extends through the femoral head. Cut-out mayoccur when the bone screw is fixedly secured to the bone nail and doesnot move in the aperture. As the femoral head moves, due to settlementof the fracture or bone deterioration, it slides or travels along thebone screw. Eventually the femoral head moves close enough to the femurthat the threaded end of the bone screw breaks through or pierces thefemoral head and extends into the hip joint.

If the bone screw is slidably fixed in the aperture, that is the bonescrew is constrained against rotation but is allowed to slidelongitudinally in the smooth bore of the aperture, compression of thefracture may cause the head of the bone screw to extend outwardsignificantly past the outer surface of the femur creating a raisedsurface that can cause pain at the hip joint. In addition, leaving thebone screw free to move with respect to the bone nail may cause the bonescrew to migrate or loosen, thus creating a risk of failure at thefracture.

The features and advantages of the disclosure will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by the practice of the disclosure withoutundue experimentation. The features and advantages of the disclosure maybe realized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims.

SUMMARY OF THE INVENTION

An apparatus for repairing a bone fracture comprising a bone screwhaving a body. The body having a socket formed in one end thereof with aplunger assembly disposed in the socket. The body further includes adetent assembly, the detent assembly including a detent member operableto move between a first position and a second position whereinpositioning the detent member in the second position secures the bodywhereby the plunger assembly includes a plunger portion that movesindependent of the body.

The detent assembly further including a lock ring and a lock sleeve. Thelock sleeve operative to act on the lock ring to move the lock ring froma first position to the second position. Wherein when the lock ring isin the second position, an outer surface of the lock ring is urgedoutward past an outer surface of the body.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the disclosure will become apparent froma consideration of the subsequent detailed description presented inconnection with the accompanying drawings in which:

FIG. 1 is a schematic view of a bone screw according to one embodimentof the present invention shown as part of a fixation system placed in anassembled condition within a long bone such as a femur;

FIG. 2 is an enlarged schematic view of a bone screw according to oneembodiment of the present invention shown extending through the proximalend of a bone nail placed in a femur;

FIG. 3 is an exploded perspective view of a bone screw according to oneembodiment of the present invention;

FIG. 4 is an exploded cross-sectional side view of a plunger assemblyfor use with a bone screw in accordance with one embodiment of thepresent invention;

FIG. 5 is an exploded cross-sectional side view of a body for use with abone screw in accordance with one embodiment of the present invention;

FIG. 6 is a cross-sectional side view of a bone screw according to thepresent invention with the plunger assembly extended;

FIG. 7 is a cross-sectional side view of a bone screw according to thepresent invention with the plunger assembly compressed;

FIG. 8 is an enlarged schematic view of a bone screw according to asecond embodiment of the present invention shown extending through theproximal end of a bone nail;

FIG. 9 is a cross-sectional view of the plunger of FIG. 11 taken alongline 9-9;

FIG. 10 is a cross-sectional view of the plunger of FIG. 9 taken alongline 10-10;

FIG. 11 is a side view of a plunger for use with a bone screw accordingto the present invention;

FIG. 12 is a side view of a guide member for use with a bone screwaccording to the present invention;

FIG. 13 is a cross-sectional view of the guide member of FIG. 12 takenalong line 13-13;

FIG. 14 is an end of view the guide member of FIG. 12;

FIG. 15 is a perspective view of the guide member of FIG. 12;

FIG. 16 is a side view of a retainer for use with a bone screw accordingto the present invention;

FIG. 17 is a cross-sectional view of the retainer of FIG. 16 taken alongline 17-17;

FIG. 18 is an end view of the retainer of FIG. 16;

FIG. 19 is a perspective view of the retainer of FIG. 16;

FIG. 20 is a side view of a body for use with a bone screw according tothe present invention;

FIG. 21 is a cross-sectional side view of a body for use with a bonescrew according to the present invention illustrating a detent memberpositioned flush with the outer surface of the body taken along lines21-21 of FIG. 20;

FIG. 22 is a cross-sectional side view, similar to that shown in FIG.21, of a body for use with a bone screw illustrating the detent memberextending outwardly past the outer surface of the body;

FIG. 23 is cross-sectional view of one end of the body of FIG. 22 takenalong the lines 23-23;

FIG. 24 is an end view of the body of FIG. 22;

FIG. 25 is an enlarged cross-sectional area taken within the circle 25of FIG. 22;

FIG. 26 is an enlarged cross-sectional area taken within the circle 26of FIG. 22;

FIG. 27 is a side view of a set screw for use with a bone screwaccording to the present invention;

FIG. 28 is a cross-sectional view taken along lines 28-28 of FIG. 27;

FIG. 29 is an end view of the set screw of FIG. 27;

FIG. 30 is a perspective view of the set screw of FIG. 27;

FIG. 31 is a side view of an alternative embodiment of a body for usewith a bone screw according to the present invention;

FIG. 32 is a cross-sectional view of the body of FIG. 31;

FIG. 33 is a perspective view of installation equipment used forinstalling a bone screw according to the present invention;

FIG. 34 is a perspective view of the installation equipment and the bonescrew;

FIG. 35 is a cross-sectional view illustrating the installationequipment connected to the bone screw according to the presentinvention;

FIG. 36 is an enlarged schematic view of a bone screw according to oneembodiment of the present invention shown extending through the proximalend of a bone nail;

FIG. 37 is a cross-sectional side view of a bone screw according to oneembodiment of the present invention with the plunger assembly extended;

FIG. 38 is a perspective view of a plunger for use with a bone screwaccording to one embodiment of the present invention;

FIG. 39 is a side view of the plunger of FIG. 38;

FIG. 40 is a cross-sectional side view of the plunger of FIG. 38 takenalong line 40-40;

FIG. 41 is an enlarged side view of one end of the plunger of FIG. 38;

FIG. 42 is a perspective view of an annular wedge for use with a bonescrew according to one embodiment of the present invention;

FIG. 43 is an end view of the annular wedge of FIG. 42;

FIG. 44 is a cross-sectional side view of the annular wedge of FIG. 43taken along line 44-44;

FIG. 45 is an enlarged side view of a portion of the annular wedge ofFIG. 42;

FIG. 46 is a perspective view of a body for use with a bone screwaccording to one embodiment of the present invention;

FIG. 47 is a top view of the body of FIG. 46

FIG. 48 is a cross-sectional side view of the body of FIG. 46;

FIG. 49 is a an enlarged partial cross-sectional side view of the bodyof FIG. 46 taken in circle 49-49;

FIG. 50 is an enlarged cross-sectional side view of one end of the bodyof FIG. 46;

FIG. 51 is an enlarged cross-sectional schematic side view of a bonescrew according to the present invention;

FIG. 52 is an enlarged cross-sectional schematic side view illustratingthe engagement between respective teeth of the annular wedge and body;

FIG. 53 is a perspective view of a lockout tube according to oneembodiment of the present invention;

FIG. 54 is a side view of the lock out tube of FIG. 53;

FIG. 55 is a perspective view of a clock ring according to oneembodiment of the present invention;

FIG. 56 is a side view of the lock ring of FIG. 55;

FIG. 57 is a cross-sectional side view of the lock ring of FIG. 55;

FIG. 58 is a perspective view of a lock sleeve according to oneembodiment of the present invention;

FIG. 59 is a side view of the lock sleeve of FIG. 58;

FIG. 60 is a cross-sectional side view of the lock sleeve of FIG. 58;

FIG. 61 is an enlarged cross-sectional schematic view illustrating thelock ring positioned flush with the outer surface of the body;

FIG. 62 is an enlarged cross-sectional schematic view illustrating thelock ring extending outwardly past the outer surface of the body;

FIG. 63 is a perspective view of a second embodiment of installationequipment used for installing a bone screw according to the presentinvention;

FIG. 64 is a cross-sectional view of the installation equipment of FIG.63 shown adjacent a bone screw according to the present invention;

FIG. 65 is an enlarged cross-sectional view of the installationequipment of FIG. 63; and

FIG. 66 is a perspective view of a lockout tube removal tool for use inremoving the lockout tube

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

For the purposes of promoting an understanding of these principles inaccordance with the disclosure, reference will now be made to theembodiments illustrated in the drawings and specific language will beused to describe the same. It will nevertheless be understood that nolimitation of the scope of the disclosure is thereby intended. Anyalterations and further modifications of the inventive featuresillustrated herein, and any additional applications of the principles ofthe disclosure as illustrated herein, which would normally occur to oneskilled in the relevant art having possession of this disclosure, are tobe considered within the scope of the disclosure claimed.

Before the present apparatus and methods for treating a bone fractureare disclosed and described, it is to be understood that this disclosureis not limited to the particular configurations, process steps, andmaterials disclosed herein as such configurations, process steps, andmaterials may vary somewhat. It is also to be understood that theterminology employed herein is used for the purpose of describingparticular embodiments only and is not intended to be limiting since thescope of the present disclosure will be limited only by the appendedclaims and equivalents thereof.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a”, “an”, and “the” include plural referentsunless the context clearly dictates otherwise. Moreover, as used herein,the terms “comprising”, “including”, “containing”, “characterized by”and grammatical equivalents thereof are inclusive or open-ended termsthat do not exclude additional, unrecited elements or method steps. Inaddition, the term “at” when referring to the location or placement ofan element or object means in, near or by the area or location occupiedby the particular structure or element referred to.

As used herein, the term “proximal” shall refer broadly to the conceptof a nearest portion.

As used herein, the term “distal” shall generally refer to the oppositeof proximal, and thus to the concept of a further portion, or a furthestportion, depending upon the context.

FIGS. 1-2 show a schematic view of a bone screw, seen generally at 10,according to the present invention as part of a fixation system, seengenerally at 12. The fixation system 12, according to one embodiment, isshown placed in an assembled condition within a bone, illustrated hereas a femur 14. The fixation system 12 includes a bone nail 16 having adistal end 18 and a proximal end 20. A passageway 22 extendslongitudinally through the bone nail 16 between the proximal end 20 andthe distal end 18. The passageway 22 receives insertion and extractioninstrumentation, such as a guide wire (not shown), used to position thebone nail 16 within the femur 14. Typically, the distal end 18 of thebone nail 16 is inserted into the femur 14 first and follows the path ofthe guide wire. Whereby, the bone nail 16 is inserted into theintramedullary cavity of the femur 14. One or more distal anchoringmembers 23 may be used to anchor the distal end 18 of the bone nail 16in place. It will be understood that the anchoring members 23 may bescrews or any other suitable variety of fastening mechanism known in theart for use with trochanteric nails. Accordingly, the shape, size andconfiguration of the anchoring members 23 may vary within the scope ofthe present disclosure. The term “nail” as used here refers to aconnective orthopedic nail implant, including but not limited to atrochanteric nail for use in a femur, as well as any other connectiveimplant device suitable for use in any bone of interest.

The proximal end 20 of the bone nail 16 includes an aperture orthroughbore 24 extending through the proximal end 20 in a directiontypically angled with respect to the longitudinal axis 26 of the bonenail 16. The bone screw 10 extends through the aperture 24 such that athreaded portion 28 of the bone screw 10 extends through the femoralneck 30 of the femur 14 and is seated within the dense cortical bone ofthe femoral head 32. The bone screw 10 preferably extends parallel tothe longitudinal axis of the femoral head 32 and femoral neck 30 whenextending through the aperture 24. The bone screw 10 spans the fractureillustrated as the jagged line 34 in the drawings.

During installation the bone screw 10 is tightened or rotated until thehead 36 of the bone screw 10 engages the outer cortex 38 of the femur 14whereby continued tightening or rotating of the bone screw 10 creates aforce that draws the femoral head 32 toward the femur 14 and compressesthe fracture 34. It will be understood that the bone screw 10 may beuseful in other types of bones, in addition to femurs, with or withoutthe bone nail 16 in accordance with the principles of the presentdisclosure. Further, additional embodiments of the present invention mayinclude using the bone screw 10 of the present invention with othertypes of side plates or supporting or reinforcing members used inorthopedic fixation systems.

Referring now to FIG. 3, an exploded perspective view is shown of oneembodiment of the bone screw 10 in accordance with the principles of thepresent invention. The bone screw 10 includes a cylindrical body orbarrel 40 with the head 36 located at a first end 42 thereof. Asillustrated, the head 36 is a lip or raised portion extending radiallyoutward from the cylindrical body 40 of the bone screw 10. The head 36operates as a stop or depth limiter whereby the head 36 of the bonescrew 10 contacts or is seated on the outer cortex 38 of the femur 14.

The cylindrical body 40 includes several interior openings or aperturesextending longitudinally along a longitudinal axis 44 of the bone screw10. One of these interior openings is formed by a cylindrical shapedsocket 46 that extends inwardly from a second end 48 of the cylindricalbody 40. The socket 46 is sized to receive a plunger assembly 50including a threaded plunger 52, a spring member 54, a guide member 56and a retainer 58.

Turning for a moment to the plunger assembly 50, the threaded plunger 52has a cylindrically shaped body including a threaded engagement portion60 and a plunger portion 62. As illustrated, in FIGS. 4 and 9-11 theplunger portion 62 has a generally smooth cylindrical outercircumferential surface 64 located adjacent the threaded engagementportion 60. The threaded engagement portion 60 includes a plurality ofhelical threads 63. The helical threads 63 utilize a thread profiletypical for use with bone screws. Detent tabs 66 extend radially outwardfrom the cylindrical outer circumferential surface 64 of the plungerportion 62. While shown with two detent tabs 66 positioned generallyopposite one another, a single or additional detent members can also beused.

The threaded plunger 52 further includes a generally cylindricalinterior cavity or chamber 68 forming an opening 70 on one end 72 of theplunger portion 62. The chamber 68 includes a plurality of internalthreads 74 extending into the chamber 68 from the end 72 of the plungerportion 62. The chamber 68 forms a generally cylindrical bore extendinginward into the plunger portion 62 and terminating at a stop surface 76.In the present embodiment, the spring member 54 is shown as a coiledcompression spring 78 sized to fit within the chamber 68.

As illustrated in FIGS. 3-4 and 12-15 the guide member 56 of the plungerassembly 50 has a generally cylindrical head 80 located on one end 82thereof. That head 80 having a radially extending flat front face 81.The guide member 56 further includes a shank portion 84 connected to thehead 80. The shank portion 84 being generally cylindrical and having aplurality of threads 86 is located adjacent an end 88 opposite the head80. A hexagonal shaped drive socket 90 is located in the end 88 of theguide member 56. While shown as having a hexagonal shape, the drivesocket 90 can be of various shapes including star or square providedthey are suitable to accept a driving tool used to rotate the guidemember 56.

As illustrated in FIGS. 3-4 and 16-19 the retainer 58 of the plungerassembly 50 includes a threaded portion 92 and a head 94. The threadedportion 92 having an outer diameter and thread configuration such thatit is complementary to and threadably received in the threads 74 of thechamber 68 of the threaded plunger 52. The head 94 is generallycylindrical in shape and includes opposing flat surfaces 96 located onthe outer peripheral surface 98 thereof. The retainer 58 furtherincludes a cylindrical aperture or bore 100 that extends through theretainer 58.

As shown in FIG. 3 the plunger assembly 50 is generally assembled byinserting the coiled compression spring 78 into the chamber 68 of thethreaded plunger 52 through the opening 70. The compression spring 78extends between the stop surface 76 and the internal threads 74 locatedat the end 72 of the threaded plunger 52. The head 80 of the guidemember 56 is inserted into the cavity or chamber 68 with the head 80 ofthe guide member 56 sized and shaped such that the head 80 slidably fitsin the generally cylindrical cavity 68. For example, in the disclosedembodiment, the chamber 68 is generally cylindrically shaped and thehead 80 of the guide member 56 is also generally cylindrically shaped.It should be understood however, that other complementary configurationscould also be used. Once the head 80 of the guide member 56 is placed inthe chamber 68 and contacts the spring 78, the retainer 58 is placedover the guide member 56 by sliding the shank portion 84 of the guidemember 56 through the aperture 100 of the retainer 58. The retainer 58slides along the shank portion 84 until the threaded portion 92 of theretainer 58 engages the complementary threads 74 located in the opening70 at the end 72 of the threaded plunger 52. The retainer 58 is thentightened using a suitable tool engaging the opposed flat surfaces 96 ofthe retainer 58 until the head 94 of the retainer 58 contacts and issecured to the end 72 of the threaded plunger 52. As illustrated in FIG.6 in the expanded or uncompressed position the compression spring 78forces the guide member 56 outward until the head 80 of the guide member56 contacts the retainer 58.

Once assembled the plunger assembly 50 is then slidably secured in anon-rotatable telescopic relationship in the socket 46 of the body 40.As illustrated in FIGS. 3-5 and 22-23 the socket 46 of the body 40includes a pair of opposed grooves or channels 102 extending radiallyoutward from the inner circumferential surface 104 of the socket 46. Thegrooves 102 are sized such that they slidably receive the detent tabs 66located on the threaded plunger 52. The grooves 102 and detent tabs 66cooperate to prevent relative rotational movement between the plungerassembly 50 and the body 40 while allowing the plunger assembly 50 tomove in a reciprocal or back and forth manner in the direction of thelongitudinal axis 44 of the body 40.

As illustrated in FIGS. 6-7 the guide member 56 is used to secure theplunger assembly 50 to the body 40. To secure the plunger assembly 50 tothe body 40, the plunger assembly 50 is inserted into the socket 46 withthe detent tabs 66 placed in the grooves or channels 102 located in thesocket 46. As illustrated in FIGS. 3-7, 20-22 and 25 the body 40includes a threaded aperture 106 extending longitudinally along thelongitudinal axis 44 of the body 40. The threads of the threadedaperture 106 are complementary to the threads 86 on the guide member 56.Accordingly, once the threads 86 of the guide member 56 contact thethreaded aperture 106 a suitable drive tool (not shown) having aconfiguration complementary to the drive socket 90 located in the end 88of the guide member 56, shown herein as having a hexagonal shape, isinserted into the body 40 from the first end 42 until it engages thedrive socket 90 of the guide member 56. Rotating the drive tool rotatesthe guide member 56 until the shoulder 108 of the guide member 56located between the threads 86 and the shank portion 84 is seated on thesurface 110 forming the base or bottom of the socket 46.

FIGS. 3-7 also illustrate a second method for installing the guidemember 56 in the threaded aperture 106, wherein a passageway 112 extendslongitudinally through the threaded plunger 52 and a drive socket isformed on the front flat face 81 located on the end 82 of the head 80.Accordingly, a drive tool may extend through the passageway 112 andengage the drive socket formed in the front flat face 81 of the end 82of the head 80 to rotate the guide member 56 and correspondingly securethe guide member 56 in the body 40.

FIGS. 6-7 show the bone screw 10 in accordance with one aspect of thepresent invention, the bone screw 10 fully extended as illustrated inFIG. 6 and fully compressed as illustrated in FIG. 7. The distance oftravel 114 of the threaded plunger 52 with respect to the body 40 isdetermined by the distance between the stop surface 116, that is theshoulder formed at the junction of the shank portion 84 and the head 80of the guide member 56, and the stop surface 110 formed at the bottom ofthe socket 46 of the body 40. Accordingly, varying the length of theshank portion 84, that is the distance between the stop surface 110 andthe shoulder 108 of the guide member 56, varies the amount of travel andcorrespondingly the amount of longitudinal compression of the bone screw10.

Varying the strength or spring constant k of the spring 78 varies thecompressive force necessary to move the threaded plunger 52 through thedistance of travel 114. For example, depending upon the weight and sizeof an individual and degree of severity of the fracture, the compressiveforce of the spring 78 can be changed or modified to provide a suitableresistance force. It should be understood that the resistance force neednot be linear, but may vary over the distance of travel 114.Accordingly, the present invention allows for compression of a fracturewhen a load is applied, for example, when a patient stands and weight istransferred from the femoral head 32 to the femur 14, if necessary, theplunger assembly 50 allows movement of the threaded plunger 52 withinthe socket 46 of the body 40 enabling compression between the femoralhead 32 and the femur 14. The preferred embodiment contemplates adistance of travel 114 of 10 mm, however this is for illustrativepurposes only and the actual degree or distance of travel 114 may begreater or less than 10 mm.

As illustrated in FIGS. 1-5, 20-22 and 26 the bone screw 10 includes adetent member, seen generally at 120 and illustrated as a finger, thatis driven radially outward by a drive assembly shown as a screw memberor set screw 150. The detent member 120 engages the bone nail 16 andmaintains a positional relationship between the body 40 of the bonescrew 10 and the bone nail 16. The detent member 120 fixes the positionof the body 40 of the bone screw 10 with respect to the bone nail 16 andprevents both sliding and rotating of the body 40 of the bone screw 10with respect to the bone nail 16. Accordingly, the detent member 120keeps the body 40 of the bone screw 10 in place while the plungerassembly 50 allows movement of the plunger member 52 independent of thebody 40 whereby any compression or sliding between the femoral head 32and femur 14 is compensated for by movement of the plunger assembly 50.

As illustrated, the body 40 includes a threaded bore 124 extendinginwardly from the first end 42 toward the threaded aperture 106. Asshown in the drawings the threaded aperture 106, which receives theguide member 56, is located between the first end 42 and the second end48 of the body 40. An internal drive socket 126 is located adjacent thefirst end 42 of the body 40. As illustrated, the drive socket 126 has ahexagonal configuration shaped to accept a hexagonal drive tool, seeFIGS. 33-35 used to rotate and install the bone screw 10.

FIGS. 20-22 and 26 illustrate the detent member 120 in greater detail.The detent member 120 of the present embodiment is a cantilevered member128 having a free end 130 and a fixed end 132. A slot 134 extends alongthe sides 136 and free end 130 of the cantilevered member 128. The freeend 130 of the cantilevered member 128 is configured such that in theinitial or first position it remains at or below the outercircumferential surface or periphery 138 of the body 40. As shown in theillustrated embodiment, the outer surface 140 of the detent number 120may move radially outward to a position past or above the outercircumferential surface or periphery 138 of the body 40. The outersurface 140 of the cantilevered member 128 may include a plurality ofridges and grooves 142, 144. While the inner surface 141 of thecantilevered member 128 has a threaded configuration identical to thethreads of the threaded bore 124.

As shown in FIG. 8 the plurality of ridges and grooves 142, 144 on theouter surface 140 of the cantilevered member 128 cooperate withcorresponding and complementary ridges and grooves, 146 148 located inthe aperture 24 extending through the proximal end 20 of the bone nail16. While the cantilevered member 128 is disclosed with a plurality ofridges and grooves 142, 144 to aid in securing the bone screw 10 to thebone nail 16, this is but one embodiment. As illustrated in FIG. 2, theouter surface 140 of the cantilevered member 128 may be smooth with thecorresponding interior surface of the aperture 24 in the proximal end 20of the bone nail 16 also being smooth. Further, it is contemplated thatthe outer surface 140 of the cantilevered member 128 may include otherconfigurations to increase the frictional or holding force between thedetent member 120 and correspondingly the bone screw 10 and the bonenail 16. In addition, other surface configurations or coatings can beutilized to increase the holding force fixing the bone screw 10 in theaperture 24. While the outer circumferential surface or periphery 138 ofthe body 40 is disclosed herein without the ridges and grooves 142, 144shown on the cantilevered member 128, the invention contemplates addingsuch ridges and grooves to the outer surface 138 of the body 40.Further, it is within the scope of the present invention to provideother types of surfaces or surface coatings that would reduce movementor rotation of the bone screw 10 with respect to the bone nail 16.

As illustrated in FIGS. 3, 20-22 and 26 one example of the driveassembly is shown in the present embodiment as a threaded member or setscrew 150 having a plurality of threads 152 located on the outerperipheral surface 154 thereof wherein the set screw 150 threadablyengages the threaded bore 124 of the body 40. The set screw 150 has ahexagonal bore 156 forming a drive socket suitable for receiving adriving tool, see FIGS. 33-35. The set screw 150 operates to urge thecantilevered member 128 radially outward as the set screw 150 travelsinwardly along the threaded bore 124. The set screw 150 urges or drivesthe free end 130 of the cantilevered member 128 outwardly as itapproaches the free end 130 since the wall or radial thickness 158 ofthe cantilevered member 128 is greater at the free end 130 of thecantilevered member 128 than the wall or radial thickness 161 at thefixed end 132 of the cantilevered member 128. Since the outer diameterof the set screw 150 remains constant, as it travels in the threadedbore 124 and along the length of the cantilevered member 128 it urgesthe free end 130 of the cantilevered member 128 outward whereby itextends above or past the outer peripheral surface 138 of the body 40 toa distance 159.

In one embodiment, the thickness of the free end 130 of the cantileveredmember 128 is increased through the following steps, during manufactureof the body 40, the body 40 is turned to a predetermined outer diameterwith a portion thereof, specifically the area where the cantileveredmember 128 will be located, having a raised portion or section having agreater outer diameter. The magnitude or difference in the respectiveouter diameters being the amount or distance 159 that the free end 130of the cantilevered member 128 will extend above or outwardly past theouter circumferential surface or periphery 138 of the body 40. In oneembodiment, the raised section may have a conical shape beginningroughly at or corresponding to the location of the free end 130 of thecantilevered member 128 and tapering off to the overall diameter of thebody 40 as it approaches the first end 42. Cutting the slot 134 formsthe cantilevered member 128. Once formed, the cantilevered member 128 isdepressed or forced inward into the threaded bore 124 while theremaining raised portion or section is removed whereby the entire outercircumferential surface or periphery 138 of the body 40 has a constantouter diameter. In the embodiment wherein the outer surface 140 of thecantilevered member 128 includes ridges and grooves 142, 144 these canbe formed prior to cutting the slot 134 and moving the free end 130 ofthe cantilevered member 128 inward prior to removing the remainingraised portion or section. It is within the scope of the presentinvention to use other means to increase the thickness of the free end130 of the cantilevered member 128 whereby as the set screw 150 travelsthrough the threaded bore 124 it urges the free end 130 outwardly suchthat it engages the aperture 24 located in the proximal end 20 of thebone nail 16. For example, additional material could be added to theouter surface 140 of the cantilevered member 128 to increase its overall thickness.

Accordingly, the present invention contemplates a detent member 120movable between a first position wherein the free end 130 of thecantilevered member 128 is positioned flush with or at the same level asthe outer peripheral surface 138 of the body 40 and a second positionwherein the free end 130 of the cantilevered member 128 extends above orpast the outer peripheral surface 138 the body 40. While shown hereinusing a cantilevered member 128 formed as an integral part of the body40, the present invention contemplates that the detent member 120 mayalso be inserted into the threaded bore 124 as a separate member whereinthe separate member is still urged outwardly by the drive assembly andstill come within the scope of the present invention.

Referring to FIGS. 31 and 32 there is shown an alternative embodiment ofa body 340 for use with a bone screw 10 of the present invention. Thebody 340 includes first and second opposed detent members, seengenerally at 342, urged outwardly by a set screw 344. The opposed detentmembers 342 are similar in design to those disclosed in the previousembodiment in that the detent members 342 include cantilevered members346 having a fixed end and a free end 348, 350. The free end 350 onceagain having a wall or radial thickness 352 greater than the wall orradial thickness at the fixed end 348. The alternative embodiment alsodiscloses the outer surface 354 of the cantilevered members 346 assmooth rather than with the ridges and grooves of the previousembodiment.

Turning now to FIGS. 33-35 an installation tool, seen generally at 200,for use in installing the bone screw 10 according to the presentinvention is shown. The installation tool 200 includes a first or outerdrive member or driver 202, a second or middle drive member or driver204 disposed within the first or outer drive member 202 and a third orinner drive member or driver 206 disposed within the second or middledrive member 204. The outer drive member 202 is a hollow rod or shafthaving a hexagonal shaped drive portion 208 located on the end 210thereof. A handle 212 is located at the opposite end and is attached tothe outer driver 202 whereby rotation of the handle 212 rotates theouter driver 202. The middle driver 204 includes a threaded portion 214located on an end 216 and the opposite end 218 of the middle driver 204includes a head 220 configured to accept a tool used to rotate themiddle driver 204 independent of the outer driver 202. The middle driver204 is also a hollow member and the inner driver 206 is nested withinthe middle driver 204. A hexagonal shaped drive member 222 is attachedto one end 224 with a handle 226 attached to the opposite end 228.

FIG. 35 illustrates the engagement between the installation tool 200 andthe bone screw 10. Specifically, the threaded portion 214 of the middledriver 204 threadably engages the threaded bore 124 and a suitable drivetool (not shown) contacts the head 220 of the middle driver whereby theoperator can tighten and securely attach the bone screw 10 to theinstallation tool 200. The outer driver 202 then slides over the middledriver 204 until the hexagonal shaped drive portion 208 engages thehexagonal shaped drive socket 126 of the bone screw 10. It should beunderstood that rotation of the handle 212 rotates the entire bone screw10 such that the operator can properly insert the bone screw 10. Oncethe bone screw 10 is placed in its proper position within the femoralhead 32, the inner driver 206 is then slid forward within the middledriver 204 until the hexagonal shaped drive portion 222 thereof engagesthe hexagonal shaped bore 156 of the set screw 150. Accordingly,rotation of the handle 226 attached to the inner driver 206correspondingly rotates and moves the set screw 150 inwardly towards thefree end 130 of the cantilevered member 128 whereby the operator forcesor drives the detent member 120 outwardly into engagement with theaperture 24 located in the proximal end 20 of the bone nail 16. Itshould be understood that the handle 226 located on the inner driver 206may have some type of torque limiting or clutch arrangement that limitsthe amount of torque applied to the set screw 150 which correspondinglylimits the force generated by the detent member 120. While notnecessary, it is contemplated that the use of such a torque limitingdevice or handle can be used to control the pressure applied by thedetent member 120 and prevent over tightening and possible damage to thebone screw 10.

FIG. 36 illustrates a schematic view of an alternative embodiment of abone screw, seen generally at 400, according to the present invention.Similar to the previous embodiment, the bone screw 400 is part of thefixation system 12 illustrated in FIG. 1. As with the previousembodiment, the bone screw 400 extends through an aperture orthroughbore 24 extending through the proximal end 20 of the bone nail 16such that a threaded portion 402 of the bone screw 400 extends throughthe femoral neck 30 of the femur 14 and into the dense cortical bone ofthe femoral head 32. The bone screw 400 spans the fracture illustratedin FIG. 1 as the jagged line 34.

As set forth more fully herein, the bone screw 400 includes acylindrical body or barrel 404 and a plunger assembly 406 including aplunger 408. Similar to the previous embodiment, the bone screw 400 mayinclude a detent assembly, seen generally at 512, including a lock ring514 that engages the body 404 of the bone screw 400 to maintain apositional relationship between the body 404 of the bone screw 400 andbone nail 16. As set forth below, the lock ring 514 helps keep the body404 of the bone screw 400 in place while the plunger assembly 406 allowsmovement of the plunger 408 independent of the body 404. The bone screw400 may include either the plunger assembly 406 or the detent assembly512, or it may include both.

FIG. 37 shows a cross-sectional side view of the bone screw 400 inaccordance with the principles of the present invention. The bone screw400 includes a cylindrical body or barrel 404 having an outercircumferential surface 410 and a socket 412 sized to receive theplunger assembly 406 which includes the plunger 408, a spring member414, a pair of retaining pins 416 and a latch or detent mechanism,illustrated in the present embodiment as a annular wedge 418. Theplunger 408 is telescopically disposed within the socket 412 located inthe cylindrical body or barrel 404. The latch or detent mechanismoperates to allow relative movement between the plunger 408 andcylindrical body or barrel 404 in one direction while limiting movementbetween the plunger 408 and cylindrical body or barrel 404 in theopposite direction. Accordingly, as the bone screw 400 is compressed theplunger 408 will move in but not out.

As illustrated in FIGS. 37-41, the plunger 408 includes a threadedportion 420 and a piston portion 422. The threaded portion having aplurality of helical threads 424 configured in a tooth profile typicalfor use with bone screws. The piston portion 422 having a generallysmooth cylindrical outer circumferential surface 426 sized to slidablyfit within the socket 412 of the cylindrical body 404. The pistonportion 422 further including a pair of longitudinally extending groovesor channels 428 located on the outer circumferential surface 426 of thepiston portion 422. While two longitudinally extending grooves 428 areshown, single or multiple grooves can also be used. The plunger 408 alsohas a longitudinally extending aperture or passageway 430 enabling theplunger assembly to pass over a guide wire used for inserting the bonescrew 400.

The plunger 408 further includes an inwardly beveled or tapered conicalportion 432 located on the piston portion 422 adjacent the end 434thereof opposite the threaded portion 402. As illustrated, the conicalportion 432 extends radially inwardly as it extends from a position nearthe end 434. The conical portion 432 terminates on one end at a frontsurface or shoulder 458. The conical portion 432 cooperates with theannular wedge 418, functioning as a latch or detent mechanism, tocontrol travel of the plunger 408 within the cylindrical body 404,specifically the socket 412 of the bone screw 400. As illustrated inFIGS. 42-45 the annular wedge 418 includes a forward or leading end 456and a rear end, an outer surface 436 having a plurality of pitched teeth438 and a beveled or tapered conical inner surface 440 extendinginwardly such that the radial thickness is greater at the forward orleading end 456. The annular wedge 418 further includes a slot 442extending the length thereof whereby the annular wedge 418 may functionas a split ring that can be expanded or compressed. The conical portion432 of the outer surface 426 of the plunger 408 is complementary to theconical inner surface 440 of the annular 418. With the forward orleading end 456 of the annular member 418 placed adjacent the frontsurface or shoulder 458 of the conical portion 432, the annular member418 may move longitudinally along the conical portion 432 of the plunger408.

As illustrated in FIGS. 51-52 the pitched teeth 438 of the annular wedge418 have a ramp surface 482 and an engagement surface 484. In addition,the pitched teeth 452 located on the inner surface 454 of the socket 412also have a ramp surface 486 and an engagement surface 488. Therespective ramp and engagement surfaces 482, 484, 486, 488 arecomplementary and operate such that as the plunger 408 slides rearwardlyinto the socket 412 of the body 404, the respective ramp surfaces 482,486 have a degree or angle enabling them to slide on one another andallow rearward movement. However, the respective engagement surfaces484, 488 have a degree or angle preventing movement in the outwarddirection or in a direction opposite the arrow 450.

In addition, while the degree of the tapered portions of the respectiveplunger 408 and annular wedge 418 is the same, the longitudinal lengthof the conical portion 432 on the plunger 408 is slightly longer thanthe width of the annular wedge 418. Whereby the annular wedge 418 mayslide on or move longitudinally along the conical portion 432 of theouter surface 426 of the plunger 408 as the annular wedge 418 is drivenradially inward by respective ramp surfaces 482, 486 and into the gap oropen area 490 created by the conical portion 432 as set forth below.

As illustrated in FIGS. 46-50, the socket 412 of the cylindrical body orbarrel 404 extends inwardly from an end 464 thereof adjacent the opening444 of the socket 412. The body 404 further includes a second socket orpassageway 468 extending inwardly from the opposite end 470 of the body404. A threaded passageway 472 extends between the respective first andsecond sockets 412, 468. Similar to the previous embodiment, the body404 further includes an internal drive socket 474 shown herein having ahexagonal configuration to accept a hexagonal drive tool used to rotateand install the bone screw 400. Adjacent the hexagonal drive socket 474is a plurality of internal threads forming a threaded bore 476 thatcorrespondingly receives the threaded portion of an installation tool,similar to that illustrated in FIG. 34.

The plunger assembly of 406 also includes a lockout tube 492 illustratedin FIGS. 53-54. The lockout tube 492 is a tubular body 494 having alongitudinal aperture or passageway 496. The lockout tube 492 includes afirst end 498 and a second end 500 with a head portion 502 locatedadjacent the second end 500. A shoulder 504 forms the transition betweenthe head portion 502 and the tubular body 494. A plurality ofright-handed threads 506 are located on the outer surface 508 of thetube body 494 adjacent the shoulder 504. The head portion 502 includes aplurality of left-handed threads 510 located on an inner surface of thepassageway 496. As set forth below, when installed in the body 404 thefirst end 498 of the lock out tube 492 will engage the end 434 of theplunger 408 when the plunger 408 is inserted into the socket 412 andprevent movement of the plunger 408 until the lockout tube 492 isremoved.

Typically, fitting together the plunger assembly 406 first requiresinserting the lockout tube 492 into the body 404 by inserting thelockout tube through the second socket or passageway 468 wherein thetubular body 494 passes through the threaded passageway 472. The tubularbody 494 continues through the threaded passageway until the threads 506of the lockout tube 492 engage the threaded passageway 472 and thelockout tube 492 is rotated to engage the threads and ultimatelytightened until the shoulder 504 of the lockout tube 492 contacts theengagement surface 478 to secure the lockout tube 492

Once the lockout tube 492 is inserted and secured, assembly continues byinserting the spring member 414 into the socket 412 through the opening444. The spring member 414 extends between a bottom or end surface 446of the socket 412 and the end 434 of the plunger 408. The spring member414 is a compression spring that operates to urge the plunger 408outwardly in a direction opposite the arrow 450, see FIG. 37. Afterinserting the spring member 414, the plunger 408 is inserted inwardlyinto the socket 412 until the end 434 of the plunger 408 contacts thefirst end 498 of the lockout tube 492 preventing further inward travel.After the plunger 408 is placed and located in the socket 412 A pair ofretaining pins 116 are placed in and extend through the respectiveapertures 448 in the cylindrical body 404. The grooves or channels 428in the plunger 408 receive the retaining pins 116 and initially act inconjunction with the lockout tube 492 to prevent movement of the plunger408 with respect to the body 404 prior to installation of the bone screw400.

In addition, the grooves or channels 428 perform several otherfunctions. They limit the longitudinal travel of the plunger 408 in thesocket 412, with the amount of travel limited by the length of thegroove or channel 428. They also prevent rotation of the plunger 408with respect to the cylindrical body 404 such that rotation of thecylindrical body 404 also rotates the plunger 408. Further, theretaining pins 416 take up any shear load existing between the plunger408 and the cylindrical body 404 occurring during insertion of the bonescrew 400 into the bone, that is, rotation of the bone screw 400.

Providing the cylindrical socket 412 and plunger 408 withcomplementarity shapes enables a telescopic relationship between the twowhile preventing respective relative rotation. Different cross-sectionsor configurations can be used, for example a square cross-section, toprevent rotation from occurring between the cylindrical body 404 andplunger 408 while allowing sliding or telescopic movement between thebody 404 and plunger 408. Such cross-sections or configurations willallow the plunger 408 to slide or move in a reciprocal manner in thedirection of the longitudinal axis of the body 404 within the socket 412while maintaining a positional relationship between the two componentsso that they rotate together.

As set forth below, after removal of the lockout tube 492, the annularwedge 418 operates in conjunction with the spring member 414 to controlthe movement of the plunger 408 within the socket 412. In the presentembodiment, the annular wedge 418 operates to limit movement of theplunger 408 only in the direction of the arrow 450. That is, the plunger408 can collapse or extend inwardly into the socket 412 when compressedagainst the spring member 414; however, once collapsed the annular wedge418 prevents the plunger 408 from returning to its pre-collapsedposition.

FIGS. 45, 49 and 51-52 illustrate the cooperation of the pitched teeth438 located on the outer surface 436 of the annular wedge 418 with thepitched teeth 452 located on the inner surface 454 of the socket 412. Asillustrated, movement of the plunger 408 with respect to the body 404 iscontrolled by cooperation between the teeth 438 of the annular wedge 418and the teeth 452 located on the inner surface 454 of the socket 412.Specifically, the complementary pitched teeth 438, 452 on the respectivesurfaces provides for a collapsible bone screw 400 having a plunger 408capable of being held in a collapsed or compressed position. The annularwedge 418 includes a slot 442. The slot 442 enables radial expansion andcontraction of the annular wedge 418. Installing the annular wedge onthe plunger 408 includes expanding the annular wedge 418 and sliding itover the rear end 434 of the plunger 408. The annular wedge 418 slidesover the rear end 434 of the plunger 408 until it engages and snaps intothe conical portion 432 of the plunger 408. The annular wedge 418 fitsloosely about the conical portion 432 of the plunger 408. Specifically,when expanded, the overall diameter of the annular wedge 418 is greaterthan the overall diameter of the plunger 408. That is, the outer surface436 or top of the pitched teeth 438 of the expanded annular wedge 418extend above the outer circumferential surface 426 of the plunger 408.

In addition, the cavity or depression 480 formed in the plunger 408 bythe inwardly tapered conical portion 432 is sized slightly larger thanthe shape of the annular wedge 418. Accordingly, when compressed, theoverall outer diameter of the annular wedge 418 is slightly less thanthe overall diameter of the plunger 408. The flat surface 452 a of thetooth 452 has the same inner diameter as the inner surface 454 of thesocket 412. Accordingly, compression of the annular wedge 418 into thecavity or depression 480 formed by the tapered conical portion 432provides necessary clearance between the inner surface 454 of the socket412 of the body 404 and the outer surface 436 of the annular wedge 418.Further, as illustrated in FIG. 52 the ramp surfaces 482 pitched teeth438 of the annular wedge 418 slide over the respective ramp surfaces 486of the pitched teeth 452 located on the inner surface 440 of the body404.

Accordingly, a load applied to the fracture that tends to compress orreduce the fracture acts against the compressive force of the spring andmoves or drives the plunger inwardly and compresses the spring 414. Asthe plunger 408 extends rearwardly, into the socket, in the direction ofthe arrow 450, the respective pitched teeth 438 of the annular wedge 418slide over the pitched teeth 452 of the inner surface 454 of thecylindrical body 404 allowing for collapse or inward travel of theplunger 408 within the socket 412, see FIG. 52. Arrows 460, 462illustrate the movement as the respective teeth 438, 452 slide over oneanother when the plunger 408 moves in the direction of the arrow 450. Asset forth above, the respective teeth 438, 452 each include a rampsurface 482, 486 and an engagement surface 484, 488. When the plunger408 is compressed inwardly the respective ramp surfaces 482, 486 operatetogether to compress the annular wedge 418 inwardly into the conicalportion 432 of the plunger 408. Specifically, the ramp surfaces 482, 486cause a cam action between the teeth 438, 452 that drives the annularwedge 418 inwardly and to the left, that is, into the gap or open area490. Placing the forward or leading edge 456 of the annular wedge 418,the edge adjacent the thicker portion of the annular wedge 418, adjacentthe shoulder or front surface 458 of the conical portion 432. Wherebythe conical portion 432 provides a recess that receives the annularwedge 418 during inward travel of the plunger 408.

As illustrated in FIG. 51, the annular wedge 418 operates to preventoutward travel of the plunger; that is, in a direction opposite thearrow 450. Since the annular wedge 418 is outwardly biased, or preloadedwith in an outwardly expanded mode, whereby the respective teeth 438,452 of the annular wedge 418 and the cylindrical body 404 are engaged,the annular wedge 418 resists any outward or forward travel by theplunger 408. Specifically, the engagement surfaces 484, 488 of therespective teeth, 438, 452 are typically pitched at an angle that doesnot to allow movement of the annular wedge 418 in a direction oppositethat of the arrow 450. In addition, the bevel or taper of the conicalportion 432 cooperates with the beveled or tapered inner surface 440 ofthe annular wedge 418. Since the respective teeth 438, 452 of theannular wedge 418 and body 404 remains in contact any forward motion ofthe annular wedge 418 is resisted by the with the respective engagementsurfaces 484, 488 of the teeth 438, 452. As illustrated in FIG. 51 anyforward movement of the plunger 480 results in the beveled surface ofthe conical portion 432 cooperating with the complementary andcorresponding beveled inner surface 454 of the annular wedge 418 anddriving the annular wedge 418 to secure contact between the respectiveengagement surfaces 484, 488 and maintain the position of the annularwedge 418. Since the annular wedge 418 remains stationary, the plunger408 cannot move outwardly in the body 404 because of the wedge-lockaction occurring between the respective beveled surfaces 432, 440. Thepresent invention provides a mechanism that allows movement in onedirection only. While both the annular wedge 418 and the plunger 408 areshown with a taper or beveled surface, a further embodiment of thepresent invention may include and annular groove in the outer surface ofthe plunger and an annular expansion ring. Further, an alternativeembodiment may have other configurations on the respective outer surface436 of the annular wedge 418 and inner surface 454 of the socket 412;for example a roughened or knurled surface.

Accordingly, the retaining pins 416 and groove or channels 428 cooperateto define the overall length of travel of the plunger 408 with respectto the cylindrical body 404; however, the annular wedge 418 cooperateswith the cylindrical body 404 to limit the travel of the plunger in onedirection only thus the bone screw 400 is collapsible only. Finally, thespring generates a predetermined amount of force, based upon the springconstant (K), resisting compression and depending upon the particularuse or environment the amount of plunger travel and strength of thespring can be modified accordingly.

FIGS. 36 and 37 also illustrate an additional embodiment of a detentassembly, seen generally at 512, used to secure the bone screw 400 to abone nail 16. As set forth with the previous embodiment, the detentmember 512 engages the bone nail 16 and maintains a positionalrelationship between the body 404 of the bone screw 400 and the bonenail 16. Thus, the detent member 512 keeps the body 404 of the bonescrew 400 in place while the plunger assembly 406 allows movement of theplunger 408 independent of the body 404 of the bone screw 400. As withthe previous embodiment, the plunger assembly 406 moves to compensatefor any compression or sliding between the femoral head 32 and femur 14.The detent assembly 512 is also suitable for use with a bone screw 400that does not include a plunger assembly 406.

The detent assembly 512 generally includes an annular member shownherein as a lock ring 514; see FIGS. 55-57, having a plurality of slotsor grooves 516 and a drive member, shown herein as a lock sleeve 518.The lock ring 514 further includes an inner surface 520 and an outersurface 522 along with respective first and second side surfaces 524,526. As illustrated in FIG. 57 the respective first and second sidesurfaces 524, 526 are tapered or beveled surfaces 524 a, 526 a extendinginwardly from the outer surface 522 toward the inner surface 520. Asillustrated, the slots or grooves 516 extend inwardly, in an alternatingmanner, from the respective side surfaces 524, 526.

FIGS. 58-60 illustrate the lock sleeve 518 as a tubular member 528having an outer surface 530 and an inner surface 532. The lock sleeve518 further includes a first end and a second end 534, 536. The firstend 534 including an outwardly extending tapered or beveled portion 538and the second end 536 including a plurality of internal threads 540 anda head portion 542. The head portion 542 having a plurality oflongitudinally extending slots or notches 544 extending inwardly fromthe second end 536. The head portion 542 may also include a shoulder 546that engages the outer cortex 38 of the femur 14 whereby continuedtightening or rotation of the bone screw 400 creates a force that drawsthe femoral head 32 toward the femur 14 and compresses the fracture 34.

FIG. 37 illustrates the lock ring 514 and lock sleeve 518 cooperatingwith the body 404 to form the detent assembly 512. As shown, the body404 has a reduced diameter shaft portion 548 extending inwardly from theend 470 of the body 404 opposite the socket 412 to an outwardly beveledor tapered shoulder 550. A plurality of threads 552 are located on theend of the reduced diameter shaft portion 548 adjacent the end 470 ofthe body 404. A plurality of tabs 564 extend longitudinally outward fromthe end 470 of the body 404.

FIGS. 61-62 illustrate operation of the detent assembly 512.Specifically, the lock ring 514 is placed on the shaft portion 548 ofthe body 504 with the inner surface 520 of the lock ring 514 placedadjacent the outer surface 554 of the shaft portion 548. The firsttapered side surface 524 a of the lock ring 514 is placed adjacent thebeveled or tapered shoulder 550 of the body 404. As illustrated, theouter surface 522 of the lock ring 514 is located at the same diameteror equal to the diameter of the outer circumferential surface 426 of thebody 404. The inner surface 532 of the lock sleeve 518 having an innerdiameter substantially the same as the outer diameter of the shaftportion 548. Accordingly, the lock sleeve 518 slides over the shaftportion 548 until the internal threads 540 of the lock sleeve 518 engagethe outer threads 552 on the shaft portion 548. As illustrated in FIG.61, the lock sleeve 518 is rotated until the beveled or tapered shoulder550 engages the second tapered side surface 526 a of the lock ring 514and the respective outer diameters of the body 404, lock ring 514 andlock sleeve 518 are the same. Whereby, the bone screw 400 slides freelyin the aperture 24 of the bone nail 16.

After the bone screw 400 is installed in the femoral head 32 andproperly located, rotation of the lock sleeve 518 operates to drive thelocking ring 514 radially outward, see FIG. 62 and into engagement withthe aperture 24 on the bone nail 16. Specifically, as the lock sleeve518 moves longitudinally in the direction illustrated by the arrow 556the combination of beveled surfaces 538, 550 on the lock sleeve 518 andbody 404 act on the complementary first and second beveled side surfaces524 a, 526 a to urge the lock ring 514 radially outward in the directionof the arrow 558. When urged radially outward, the outer surface 522 ofthe lock ring 514 engages the inner surface of the aperture 24 in thebone nail 16 and creates a lock between the bone screw 400 and bone nail16.

The slots or grooves 516 on the lock ring 514 operate to further secureand create a lot between the bone screw 400 and bone nail 16. The slots516 are staggered or alternate between the respective first and secondside surfaces 524, 526. When the lock ring 514 is urged radially outwardthe respective sides 560 of the slots 516 create an edge 562 thatengages the inner surface of the aperture 24 to further lock the bonescrew 400 in position on the bone nail 16. Primarily, the slots 516provide additional means to resist rotation of the bone screw 400 withrespect to the bone nail 16. In addition, the outer surface 522 of thelock ring 514 may have a roughened surface finish to assist in creatingmechanical lock between the bone screw 400 and bone nail 16.

Once the lock sleeve 518 is rotated sufficiently to create a lockingforce between the lock ring 514 and aperture 24 of the bone nail 16 tosecure the bone screw 400 to the bone nail 16, the tabs 564 can be bentover such that they engage the slots or notches 544 in the lock sleeve518. Doing so prevents rotation of the lock sleeve 518 and maintains alock between the bone screw 400 and bone nail 16.

FIGS. 63-65 illustrate a second embodiment of an installation tool, seengenerally at 600, operative to engage the body 404 adjacent the end 470of the bone screw 400. The installation tool 600 includes a first orinner member or capture rod 602. The capture rod 602 has a plurality ofthreads 604 on one end thereof. The threads 604 are complementary to andengage the plurality of threads 476 located in the end 470 of the bonescrew 400. On the opposite end of the capture rod 602 is a knob 606 usedto rotate the capture rod 602.

The installation tool 600 further includes a second or middle drivemember or driver 608 disposed over the capture rod 602. As illustrated,the middle drive member 608 is a hollow rod or shaft having a hexagonalshaped drive portion 610 located on one end thereof. The hexagonalshaped drive portion 610 is complementary to and engages the internaldrive socket 474. The middle drive member 608 includes a T-handle 612spaced from the hexagonal shaped drive portion 610. The T-handle 612used to rotate the middle drive member 608.

The installation tool 600 also includes a third or outer drive member ordriver 614. The outer drive member 614 is a hollow rod or shaft withboth the middle drive member 608 and capture rod 602 disposed therein.The outer drive member 614 includes a plurality of axially extendingengagement fingers 616 located on one end thereof. The engagementfingers 616 complementary to and adapted to engage the slots or notches544 located in the head portion 542 of the lock sleeve 518. The outerdrive member 614 also includes a T-handle 618 spaced from the engagementfingers 616. The T-handle 618 used to rotate the outer drive member 614.Accordingly, as illustrated the inner member or capture rod 602, middledrive member 608 and outer drive member 614 are arranged in a nestedrelationship wherein each one rotates and moves axially independently ofthe others.

FIGS. 63-65 illustrates the engagement between the installation tool 600and the bone screw 400. Specifically, the threads 604 of the capture rod602 engage the threads 476 located in the end 470 of the bone screw 400to attach the bone screw 400 to the installation tool 600. The innerdrive member 608 slides over the inner member or capture rod 602 untilthe hexagonal shaped drive portion 610 engages the hexagonal shapeddrive socket 474. Accordingly, rotation of the T-handle 612 of the innerdrive member rotates the entire bone screw 400 such that the operatorcan properly insert the bone screw 400.

Once the bone screw 400 is placed in its proper position within thefemoral head 32, the third or outer drive member is rotated using theT-handle 618 to turn or rotate the lock sleeve 518 wherein the internalthreads 540 of the lock sleeve 518 that engage the outer threads 552 onthe shaft portion 548 cause the lock sleeve 518 to move axially alongthe body 404 of the bone screw 400. Continued rotation of the locksleeve 518 causes the beveled or tapered shoulder 550 of the lock sleeve518, which engages the second tapered side surface 526 a of the lockring 514, to drive the locking ring 514 radially outward and intoengagement with the aperture 24 on the bone nail 16.

The installation tool 600 further includes a latch mechanism 620operative to engage or latch the outer drive member 614 to the second orinner drive member 608 such that they rotate together. Specifically, theouter drive member 614 rotates with the inner drive member 608 when theT-handle 612 of the inner drive member 608 is used to install the bonescrew 400. After installation of the bone screw 400, the operator slidesthe latch mechanism 620 rearwardly, in the direction of the arrow 622,to disengage an end 624 of the latch mechanism 620 from a detent groove626 located in the T-handle 618 of the outer drive member 614. As shownherein the latch mechanism 620 is slidably mounted to the inner drivemember 608 such that it slides on but does not rotate about the innerdrive member 608. In one embodiment thereof, the latch mechanism 620 canbe biased, through a compression spring, into engagement with theT-handle 618 of the outer drive member 614. Accordingly, once the bonescrew 400 is installed the operator pulls the latch mechanism 620 bygrasping the arms 628 and pulling the latch mechanism 620 in thedirection of the arrow 622 against the spring until the end 624disengages from the detent groove 626. Once the latch mechanism 620 isdisengaged, the T-handle 618 is used to rotate the outer drive member614 and correspondingly the lock sleeve 518 to urge the lock ring 514radially outward.

After the installation tool 600 and is removed, a lockout tube removaltool 630, see FIG. 66, is used to withdraw or remove the lock out tube492. The lockout tube removal tool 630 has a left-hand threaded portion632 that engages the left-hand threads 510 located in the head 502 ofthe lockout tube 492. Using the handle 636 the lockout tube removal tool630 is rotated until the shoulder 634 fully engages the threads 502 ofthe lockout tube 492. Since the respective threads of the lockout tube492 and removal tool 630 are left-handed continued rotation of thelockout tube removal tool 630 causes the lockout tube 492 to rotate,since the threads 506 on the outer surface 508 are right-handed, andultimately be removed from the bone screw 400 through the second socketor passageway 468. Once the lockout tube 492 is removed the bone screw400 may collapse as set forth herein.

While the installation tool 600 includes an outer drive member 614operative to engage and rotate the lock sleeve 518, as set forth above,a bone screw 400 according to the present invention may not utilize thespecific detent assembly 512 including the lock ring 514. In that event,the installation tool may be modified. Further, to the extent that thebone screw 400 does not include a plunger assembly 406 then the lockouttube 492 and lockout tube removal tool 630 would not be necessary.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

What is claimed is:
 1. An apparatus for repairing a bone fracturecomprising: a bone screw having a body; and a detent assembly, saiddetent assembly including an annular member movably supported on saidbody, said annular member having an inner surface, an outer surface, afirst side surface and a second side surface, said annular member havingan opening extending between said inner surface and said outer surface;said annular member movable between a first and a second positionwherein positioning said annular member in said second position operatesto secure said body from movement relative to a bone nail; a drivemember, said drive member operative to engage said annular member andmove said annular member towards said second position; said annularmember having a first beveled surface and a second beveled surface; saidbody having a beveled surface; and said drive member having a beveledsurface wherein said first beveled surface of said annular memberengages said beveled surface of said body and said second beveledsurface of said annular member engages said beveled surface of saiddrive member.
 2. An apparatus as set forth in claim 1 wherein said drivemember includes a threaded portion.
 3. An apparatus as set forth inclaim 1 wherein said second position of said annular member includes atleast a portion of said annular member extending above and past an outersurface of said body.
 4. An apparatus as set forth in claim 1 whereinsaid outer surface engages the bone nail, said outer surface configuredto increase a holding force and correspondingly reduce movement of thebody with respect to the bone nail.
 5. An apparatus as set forth inclaim 1 wherein said opening includes a plurality of grooves.
 6. Anapparatus as set forth in claim 1 wherein said opening includes aplurality of alternating slots, each slot extending inwardly from a sidesurface.
 7. An apparatus as set forth in claim 6 wherein said body has asocket formed in one end thereof and a plunger assembly disposed in saidsocket.
 8. An apparatus as set forth in claim 7 wherein said plungerassembly includes a threaded plunger disposed in the socket formed inone end of said body; and a spring member located between said threadedplunger and said body.
 9. An apparatus for repairing a bone fracturecomprising: a body; and a detent assembly on said body, said detentassembly movable between a first and a second position whereinpositioning said detent assembly in said second position operates tosecure said body from movement relative to a bone nail; a detent memberand a drive member, said drive member operative to engage said detentmember and move said detent member towards said second position; saiddetent member includes a lock ring and said drive member includes a locksleeve, each of said lock ring and said lock sleeve disposed on saidbody; said lock ring having a first beveled surface and a second beveledsurface; said body having a beveled surface; said lock sleeve having abeveled surface wherein said first beveled surface of said lock ringengages said beveled surface of said body and said second beveledsurface of said lock ring engages said beveled surface of said locksleeve; and said lock ring includes an outer surface and a plurality ofopenings located in said outer surface.
 10. An apparatus as set forth inclaim 9 including: said body having a threaded portion; and said locksleeve having a tubular configuration and a plurality of internalthreads, said threaded portion of said lock sleeve engaging saidthreaded portion of said body wherein rotation of said lock sleeve movessaid lock ring outwardly past an outer peripheral surface of the bodyand towards said second position.
 11. An apparatus as set forth in claim10 wherein said body has a socket formed in one end thereof and aplunger assembly disposed in said socket.
 12. An apparatus as set forthin claim 9 wherein said plurality of openings located in the outersurface form alternating slots, each slot extending inwardly from a sidesurface.
 13. An apparatus as set forth in claim 12 including a plungerassembly movably supported on said body.
 14. An apparatus as set forthin claim 9 including a plunger assembly movably supported on said body.15. A bone screw for use in combination with a bone nail to treat a bonefracture comprising: a body, said body having a socket formed in one endthereof and a plunger assembly disposed in and extending outwardly fromsaid socket in a telescopic relationship; a radially outwardly movableannular member located on said body, said annular member movable betweena first and a second position wherein said second position of saidannular member operates to secure said body from movement relative tothe bone nail; said annular member having an inner surface and an outersurface; said annular member having an aperture extending between saidinner surface and said outer surface; and a tubular member located onsaid body and operative to engage said annular member and move saidannular member towards said second position.
 16. A bone screw as setforth in claim 15 including: said body having a shaft portion, saidannular member located on said shaft portion and said tubular memberlocated on said shaft portion wherein said tubular member engages saidannular member.
 17. A bone screw as set forth in claim 16 including:said annular member having a first beveled surface and a second beveledsurface; said tubular member including a lock sleeve having a beveledsurface; and said body having a beveled surface, said first beveledsurface of said annular member engaging said beveled surface of saidbody and said second beveled surface of said annular member engagingsaid beveled surface of said lock sleeve.
 18. A bone screw for use incombination with a bone nail to treat a bone fracture comprising: abody, said body having a socket formed in one end thereof and a plungerassembly disposed in said socket; a radially outwardly movable annularmember located on said body, said annular member movable between a firstand a second position wherein said second position of said annularmember operates to secure said body from movement relative to the bonenail; said annular member having an inner surface and an outer surface;said annular member having an aperture extending between said innersurface and said outer surface; a tubular member located on said bodyand operative to engage said annular member and move said annular membertowards said second position; said body having a shaft portion, saidannular member located on said shaft portion and said tubular memberlocated on said shaft portion wherein said tubular member engages saidannular member; said annular member having a first beveled surface and asecond beveled surface; said tubular member including a lock sleevehaving a beveled surface; said body having a beveled surface, said firstbeveled surface of said annular member engaging said beveled surface ofsaid body and said second beveled surface of said annular memberengaging said beveled surface of said lock sleeve; and wherein saidshaft portion includes a threaded portion and said lock sleeve includesa threaded portion engaging said threaded portion of said shaft portionsuch that rotation of said locking sleeve about said shaft portion movessaid annular member towards said second position.
 19. A bone screw asset forth in claim 18 wherein said plunger assembly includes a threadedplunger disposed in the socket formed in one end of said body; and aspring member located between said threaded plunger and said body.